Water treating device

ABSTRACT

A water treating device includes a water container for containing water; an electrolyzing chamber for sterilizing water; a water treatment line which couples the electrolyzing chamber with the water container; a sensor for measuring residual chlorine concentration; and a device for controlling the amount of the water to be electrochemically decomposed in the electrolyzing chamber on the basis of the residual chlorine concentration measured by the sensor to keep the residual chlorine concentration of the water to be fed back into the water container within a predetermined range. A bypass line is provided which is branched from the water treatment line upstream of the electrolyzing chamber for sampling the water, introducing the sampled water into the sensor for the measurement of the residual chlorine concentration thereof, and discharging the sampled water into the electrolyzing chamber after the measurement.

TECHNICAL FIELD

The present invention relates to a novel water treating device which iscapable of sterilizing water contained in various types of watercontainers ranging from large-scale water containers such as swimmingpools and bathing pools in bathhouses to medium-scale water containerssuch as water supply tanks on building rooftops and small-scale watercontainers such as bathtubs for general domestic use.

PRIOR ART

To maintain the quality of water in indoor and outdoor swimming pools orin bathing pools in hotels and public bathhouses, for example, the wateris periodically sterilized by adding so-called chlorinated lime(bleaching powder or high-concentration bleaching powder) or an aqueoussolution of sodium hypochlorite (NaClO) to the water in the pools.

Conventionally, this operation is manually performed by workers in aswimming pool or a bathhouse. In addition, the chlorinated lime and thesodium hypochlorite aqueous solution are irritating, so that carefulattention should be paid when the operation is performed in businesshours. Thus, there is a problem that greater efforts are required forthe operation. Furthermore, the chlorinated lime is in a solid powderyform, so that it takes some time for homogeneous dissolution of thechlorinated lime after the addition thereof. Thus, there is a problemthat the swimming or bathing pool is not available until the completionof the dissolution.

In the case of water supply tanks on building rooftops and bathtubs forgeneral domestic use, the water sterilization currently relies only on asterilizing capability of chlorine ions contained in tap water withoutthe addition of chlorinated lime or sodium hypochlorite. Therefore, someof the water supply tanks are found to have a deteriorated water qualitydue to proliferation of algae.

For a domestic-use bathtub, the water is generally changed everyday orevery second day and, hence, there is seemingly no problem associatedwith the water quality. However, the interior of the boiler connected tothe bathtub cannot frequently be cleaned, so that germs and mold areliable to proliferate. Accordingly, there is the fear of thedeterioration of the water quality in the bathtub.

The inventor of the present invention previously invented a watertreating device which is adapted to introduce to-be-treated water intoan electrolyzing chamber from any of the aforesaid various watercontainers and sterilize the water by way of an electrochemical reaction(see Japanese Patent Application No. HEI 11-357938).

In the water treating device of the preceding invention, theto-be-treated water is supplied into the electrolyzing chamber havingelectrodes, and subjected to the electrochemical reaction (so-calledelectrolysis) Chlorine gas, hypochlorous acid (HClO), hypochlorite ionsand the like are generated through the electrochemical reaction, anddissolved in the to-be-treated water, whereby the to-be-treated water issterilized.

In the water treating device of the preceding invention, a branch waterpath is provided for sampling the to-be-treated water before the wateris introduced into the electrolyzing chamber, and a residual chlorinesensor is provided in the branch water path for measuring the residualchlorine concentration of the to-be-treated water. The water havingpassed through the residual chlorine sensor is drained into a waterdrainage.

The residual chlorine sensor has a very small intake capacity and,hence, should be provided in the dedicated branch water path. Further, avery small amount of the water flows through the branch water path, sothat the amount of waste water drained into the water drainage is verysmall. This is why the residual chlorine sensor is provided in thebranch water path and the water subjected to the measurement of theresidual chlorine concentration is drained into the water drainage butnot into a water path.

However, the measurement of the residual chlorine concentration isconstantly performed during the operation of the water treating deviceand, therefore, the waste water is constantly produced during theoperation, resulting in poorer economy. Accordingly, there is a demandfor modifying the construction so as not to produce the waste water.

In the case of the domestic-use bathtub which has a smaller volume thanthe swimming pool or the like, the amount of the waste water resultingfrom the measurement of the residual chlorine concentration is notnegligible.

In the water treating device of the preceding invention, a float switchis provided for controlling the level of the to-be-treated water in theelectrolyzing chamber within a constant range, and the amount of thewater to be introduced into the electrolyzing chamber is controlled.

The float switch has a float which is vertically slidable according to achange in the water level. The float has a permanent magnet, so that thevertical position of the permanent magnet (float) is detected by asensor which senses the magnetism of the permanent magnet.

When minute air bubbles generated by the electrolysis rise toward thesurface of the to-be-treated water and break on the water surface, theto-be-treated water are scattered to reach a sliding member of thefloat, and fatty components contained in the to-be-treated water andchlorine compounds contained in an electrolytic solution are liable toadhere to the sliding member of the float. This may hinder the slidingof the float, and possibly cause erroneous detection of the water leveldue to a sliding failure.

When the float switch malfunctions, the water level in the electrolyzingchamber cannot be controlled within the predetermined range, so that theto-be-treated water overflows the electrolyzing chamber, resulting in ashort circuit and electric leakage. Particularly, where theto-be-treated water contains the chlorine compounds in a highconcentration, there is the fear of a problem associated with corrosiondue to the overflowing to-be-treated water.

Further, ON and OFF points of the float switch for the water leveldetection are located at substantially the same positions, so that apump for introducing the to-be-treated water into the electrolyzingchamber is switched at shorter ON/OFF intervals. This may reduce theservice lives of the pump and drivers such as an electromagnetic switchfor driving the pump.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel watertreating device which is capable of safely and properly performing asterilizing process to solve the aforesaid problems.

In accordance with an inventive aspect of the invention, there isprovided a water treating device, which comprises: a water container forcontaining water to be treated; an electrolyzing chamber for sterilizingthe to-be-treated water by way of electrochemical decomposition byenergization of an electrode set consisting of at least two electrodeplates; a water treatment line through which the to-be-treated water isintroduced into the electrolyzing chamber from the water container andfed back into the water container after the sterilization of the waterin the electrolyzing chamber; a residual chlorine sensor for measuringthe residual chlorine concentration of the to-be-treated water beforethe water is introduced into the electrolyzing chamber; and controlmeans for controlling the amount of the to-be-treated water to besubjected to the electrochemical decomposition in the electrolyzingchamber on the basis of the residual chlorine concentration measured bythe residual chlorine sensor to keep the residual chlorine concentrationof the water to be fed back into the water container within apredetermined range; wherein a bypass line is provided which is branchedfrom the water treatment line at a position upstream of theelectrolyzing chamber for sampling the to-be-treated water, introducingthe sampled to-be-treated water into the residual chlorine sensor forthe measurement of the residual chlorine concentration of the sampledto-be-treated water, and discharging the sampled to-be-treated waterinto the electrolyzing chamber after the measurement.

In accordance with another inventive aspect of the invention, theresidual chlorine sensor is located at a position upper than theelectrolyzing chamber in the bypass line in the water treating device.

In accordance with another inventive aspect of the invention, there isprovided a water treating device, which comprises: a water container forcontaining water to be treated; an electrolyzing chamber for causingelectrochemical decomposition by energization of an electrode setconsisting of at least two electrode plates; a feed line for filling theelectrolyzing chamber with an electrolytic solution containing chlorineions and having a function of promoting the electrochemicaldecomposition and, in this state, producing a sterilizing liquid havinga sterilizing capability by way of electrolysis of the electrolyticsolution by the energization of the electrode set, and supplying theproduced sterilizing liquid into the water container; a residualchlorine sensor for measuring the residual chlorine concentration of theto-be-treated water; and introduction amount controlling means forcontrolling the amount of the sterilizing liquid to be introduced intothe water container on the basis of the residual chlorine concentrationof the to-be-treated water measured by the residual chlorine sensor;wherein a bypass line is provided which is connected to the watercontainer for introducing the to-be-treated water into the residualchlorine sensor from the water container for the measurement of theresidual chlorine concentration of the to-be-treated water, and feedingthe introduced to-be-treated water back into the water container afterthe measurement.

In accordance with a further inventive aspect of the invention, a filterdevice for filtering the to-be-treated water taken out of the watercontainer and a constant flow rate valve for controlling the flow rateof the to-be-treated water filtered by the filter device at asubstantially constant level are provided upstream of the residualchlorine sensor in the water treating device.

In accordance with a further inventive aspect of the invention, theresidual chlorine sensor is a residual chlorine sensor of in-line typein the water treating device.

In accordance with an inventive aspect of the invention, there isprovided a water treating device, which comprises: a water container forcontaining water to be treated; an electrolyzing chamber for causingelectrochemical decomposition by energization of an electrode setconsisting of at least two electrode plates; a water treatment linethrough which the to-be-treated water is introduced into theelectrolyzing chamber from the water container and fed back into thewater container after sterilization of the water by the electrochemicaldecomposition in the electrolyzing chamber; water level detecting meansfor detecting a water level in the electrolyzing chamber; and waterlevel controlling means for controlling the amount of the to-be-treatedwater to be introduced into the electrolyzing chamber on the basis ofwater level data from the water level detecting means to keep the waterlevel in the electrolyzing chamber at a predetermined level; wherein thewater level detecting means has at least two electrodes disposed inspaced opposed relation and is adapted to detect the water level on thebasis of whether an electric current flows between the electrodes.

In accordance with another inventive aspect of the invention, there isprovided a water treating device, which comprises: a water container forcontaining water to be treated; an electrolyzing chamber for causingelectrochemical decomposition by energization of an electrode setconsisting of at least two electrode plates; a feed line for filling theelectrolyzing chamber with an electrolytic container containing chlorineions and having a function of promoting an electrochemical reaction and,in this state, producing a sterilizing liquid having a sterilizingcapability by way of the electrochemical decomposition of theelectrolytic solution by the energization of the electrode set, andsupplying the produced sterilizing liquid into the water container;water level detecting means for detecting a water level in theelectrolyzing chamber; and water level controlling means for controllingthe amount of the sterilizing liquid to be introduced into theelectrolyzing chamber on the basis of water level data from the waterlevel detecting means to keep the water level in the electrolyzingchamber at a predetermined level; wherein the water level detectingmeans has at least two electrodes disposed in spaced opposed relationand is adapted to detect the water level on the basis of whether anelectric current flows between the electrodes.

In accordance with a further inventive aspect of the invention, theelectrolyzing chamber comprises a tank for storing therein the producedsterilizing liquid and feeding the stored sterilizing liquid back intothe water container as required, and the water level controlling meanscontrols the amount of the sterilizing liquid to be produced in theelectrolyzing chamber on the basis of the data from the water leveldetecting means to keep the level of the sterilizing liquid stored inthe tank at a predetermined level in the water treating device.

In accordance with an inventive aspect of the invention, the water leveldetecting means is disposed in a space other than an inter-electrodespace in the electrolyzing chamber in the water treating device.

In accordance with an inventive aspect of the invention, a resinseparator for separating the electrode plates of the electrolyzingchamber from the electrodes of the water level detecting means isdisposed between the electrode plates and the electrodes in the watertreating device.

In accordance with an inventive aspect of the invention, the electrodesof the water level detecting means are composed of a metal of titaniumor a titanium alloy in the water treating device.

With this arrangement, the to-be-treated water subjected to themeasurement of the residual chlorine concentration in the bypass line isreturned into the electrolyzing chamber, so that no waste water isproduced. The to-be-treated water returned into the electrolyzingchamber is sterilized in the electrolyzing chamber and, thereafter, fedback into the water container. Therefore, water yet to be sterilized isnot fed back into the water container.

The to-be-treated water can flow into the electrolyzing chamber bygravity after the residual chlorine concentration thereof is measured bythe residual chlorine sensor. Therefore, the to-be-treated water isreturned into the electrolyzing chamber without the use of a pump or thelike, so that the costs of the system can be reduced.

The residual chlorine concentration of the to-be-treated water can bemeasured on a real-time basis in the water treating device employing thebatch-type electrolyzing chamber. Further, the water is fed back intothe water container after the measurement of the residual chlorineconcentration, so that water saving can be achieved without theproduction of the waste water which may be entailed in the prior art.This arrangement is particularly effective in the case of a domestic-usebathtub which has a smaller volume than a swimming pool or the like.

The residual chlorine sensor of in-line type can be employed, so that aposition at which the residual chlorine sensor is installed can moreflexibly be determined.

The water level may be detected on the basis of whether the electriccurrent flows between the electrodes. Therefore, erroneous detection ofthe water level is less liable to occur in the absence of a movablemember such as a conventional float switch.

Where the number of the electrodes of the water level detecting means isincreased to three or more, a plurality of water level detectingpositions can be set. Thus, the water level can be controlled moreprecisely.

Adverse effects on the electrodes of the water level detecting means andmalfunction of the water level detecting means are prevented with theinvention, which may otherwise occur due to the electric current flowingbetween the electrodes for the electrolysis, thereby ensuring accuratemeasurement of the water level.

The corrosion of the electrodes can drastically be retarded as comparedwith a case where the electrodes are composed of stainless steel oriron. Therefore, the electrodes are free from replacement for a longperiod of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically illustrating a water treating deviceaccording to a first embodiment of the present invention;

FIG. 2 is a schematic sectional view of an air/liquid separation chamberwhich is a major portion of the water treating device according to thefirst embodiment of the present invention;

FIG. 3 is a schematic top view of the air/liquid separation chamberwhich is the major portion of the water treating device according to thefirst embodiment of the present invention;

FIG. 4 is a block diagram illustrating the electrical construction ofthe water treating device according to the first embodiment of thepresent invention;

FIG. 5 is a schematic sectional view of a residual chlorine sensoremployed in the water treating device according to the first embodimentof the present invention;

FIG. 6 is a diagram schematically illustrating a water treating deviceaccording to a second embodiment of the present invention;

FIG. 7 is a schematic sectional view of a batch process electrolyzingchamber which is a major portion of the water treating device accordingto the second embodiment of the present invention;

FIG. 8 is a schematic top view of the batch process electrolyzingchamber which is the major portion of the water treating deviceaccording to the second embodiment of the present invention;

FIG. 9 is a schematic sectional view of a residual chlorine sensoremployed in the water treating device according to the second embodimentof the present invention;

FIG. 10 is a diagram schematically illustrating a water treating deviceaccording to a third embodiment of the present invention;

FIG. 11 is a block diagram illustrating the electrical construction ofthe water treating device according to the third embodiment of thepresent invention;

FIG. 12 is a flow chart for explaining the flow of a control process tobe performed by a control section shown in FIG. 11, particularly, awater level detecting process to be performed in an air/liquidseparation chamber by employing a water level sensor; and

FIG. 13 is a flow chart for explaining the flow of a control process tobe performed by the control section shown in FIG. 11, particularly, awater level detecting process to be performed in a batch processelectrolyzing chamber by employing a water level sensor.

EMBODIMENTS OF THE INVENTION

FIG. 1 is a diagram schematically illustrating the construction of awater treating device 1 incorporated in a large-scale water container 2such as a swimming pool or a bathing pool in a bathhouse in accordancewith a first embodiment of the present invention.

Referring to FIG. 1, the water container 2 is provided with a maincirculation line 20. The main circulation line 20 is provided with acirculation pump 22. Water is pumped out of the water container 2,circulated in a direction indicated by double-line arrows in the maincirculation line 20, and fed back into the water container 2 by thecirculation pump 22. A filter 21 for sand filtration of organicsubstances and a heat exchanger 23 for heating and cooling thecirculated water are disposed downstream of the circulation pump 22 inthe main circulation path 20.

A water treatment line 10 is diverged from the main circulation line 20at a branch J1 located downstream of the filter 21 and upstream of theheat exchanger 23. The water treatment line 10 joins the maincirculation line 20 at a junction J2 located downstream of the heatexchanger 23.

An air/liquid separation chamber 13 and the following devices areprovided in the midst of the water treatment line 10. A stop valve B1,regulation valves B2, B3 for flow rate regulation, a flow rate meter S1,and an electromagnetic valve B4 are disposed in this order in a pathextending from the branch J1 to the air/liquid separation chamber 13.

A feed pump P1 for circulating to-be-treated water in the watertreatment line 10, a flow rate meter S4, a regulation valve B7, a checkvalve B8 for prevention of back flow, and a regulation valve B9 for flowrate regulation are disposed in this order downstream of the air/liquidseparation chamber 13 toward the junction J2 in the water treatment line10.

A bypass line 11 is diverged from the water treatment line 10 at aposition between the regulation valves B2 and B3. The to-be-treatedwater flowing in a direction indicated by solid-line arrows in the watertreatment line 10 is partly permitted to flow into the bypass line 11. Aregulation valve B12 for flow rate regulation, and a residual chlorinesensor 26 for measuring a residual chlorine concentration are disposedin this order in the bypass line 11. An end portion 11 a of the bypassline 11 extending downstream of the residual chlorine sensor 26 servesas a drain port, which communicates with a space above a water surfacein the air/liquid separation chamber 13. Thus, the to-be-treated waterdischarged from the drain port 11 a is exposed to the atmosphere, anddischarged into the air/liquid separation chamber 13.

Referring to FIGS. 2 and 3, an explanation will be given to theconstruction of the air/liquid separation chamber 13.

The box-shaped air/liquid separation chamber 13 has a cover 13 e whichcovers an open top 13 c of the air/liquid separation chamber 13. Afilter 12 for removal of minute air bubbles is disposed within theair/liquid separation chamber 13 to divide the air/liquid separationchamber 13 into a region 13 a and a region 13 b. An electrode set E1consisting of a plurality of electrode plates is disposed in the region13 a on an upstream side. The region 13 a in which the electrode set E1is disposed serves as an electrolyzing chamber for an electrochemicalreaction.

Further, a water level sensor W1 is provided in the region 13 a. Aseparator 30 separates the electrode set E1 from the water level sensorW1. The separator 30 is composed of a resin such as of vinyl chloride orpolypropylene, and includes a separation plate 30 a disposed between theelectrode set E1 and the water level sensor W1 to divide the region intotwo regions with a margin left on one side as a water passage, and aplurality of separation plates 30 b disposed perpendicularly to theseparation plate 30 a in staggered parallel relation in the region wherethe electrode set E1 is disposed. The separator 30 (30 a and 30 b)prevents malfunction of the water level sensor W1, which may otherwiseoccur when an electric current flowing through the electrode set E1reaches electrode rods of the water level sensor W1 because theelectrode set E1 is disposed on the upstream side and the water levelsensor W1 is disposed on the downstream side.

An electrical conductivity sensor 24 and a PH sensor 25 attached to thecover 13 e are located in the region 13 a. The electrical conductivitysensor 24 and the PH sensor 25 are separated from the electrode set E1by the separation plates 30 b. Thus, the electric current flowingthrough the electrode set E1 is prevented from reaching the electricalconductivity sensor 24 or the PH sensor 25 for prevention of adverseeffects on detection capabilities of the sensors.

The water level sensor W1 includes, for example, five electrode rods SW1to SW 5 having different lengths. The electrode rod SW5 is a commonelectrode rod located at the lowermost position in the air/liquidseparation chamber 13. The electrode rod SW4 is an electrode rod fordetection of a water level for giving an alarm on abnormal watershortage, and the electrode rod SW3 is an electrode rod for detecting alower limit water level for clearing the alarm on the abnormal watershortage. The electrode rod SW2 is an electrode rod for detecting anupper limit water level, and the electrode rod SW 1 is an electrode rodfor detecting a water level for giving an alarm on an abnormal waterfull state.

The electrode rod SW1 is located at a position upper than the electroderod SW2 for detecting the upper limit water level so as to sense thatthe water level in the air/liquid separation chamber 13 exceeds theupper limit water level due to some abnormality of the system. Theelectrode rod SW4 is located at a position lower than the electrode rodSW3 for detecting the lower limit water level so as to sense that thewater level is lowered below the lower limit water level due to someabnormality of the system.

The electrode rods SW1 to SW5 of the water sensor W1 are preferablycomposed of a material such as titanium (Ti) or a titanium alloy whichhas corrosion resistance with respect to hypochlorous acid andhypochlorite ions contained in the electrolyzed water.

The water level sensor W1 is attached to a central portion of the cover13 e, and the five electrode rods SW1 to SW5 extend into the air/liquidseparation chamber 13.

A constant voltage or a constant electric current is supplied to thecommon electrode SW5 from a power supply not shown, and a detectionsection not shown is connected to the electrode rods SW1 to SW4. Whenthe electrode rod SW4 is submerged in the water, for example, theelectrode rod SW5 and the electrode rod SW4 are electrically connectedto each other via an electric resistance of the water. As a result, thedetection section senses that the water level is reached, on the basisof a fact that the detected electric current or voltage of the electroderod SW4 reaches a level greater than a reference value.

On the basis of the level of the to-be-treated water in the region 13 adetected by the water level sensor W1, the opening and closing of thestop valve B1 and the flow rate regulation at the regulation valve B2are controlled, whereby the amount of the to-be-treated water to beintroduced into the air/liquid separation chamber 13 is controlled.Further, the flow rate of the to-be-treated water fed by the feed pumpP1 is controlled to keep the level of the to-be-treated water in theregion 13 a at a predetermined water level.

The to-be-treated water flowing in the water treatment line 10 passesthrough the electromagnetic valve B4, and then flows through the cover13 e into the region 13 a in which the electrode set E1 is disposed.

The to-be-treated water flowing in the bypass line 11 and the residualchlorine sensor 26 also flows through the cover 13 e into the region 13a in which the electrode set E1 is disposed. A port of the watertreatment line 10 and the open end portion 11 a of the bypass line 11are disposed above a normal water surface in the region 13 a, so thatthe to-be-treated water is exposed to the atmosphere and then flows intothe region 13 a.

An outlet port 13 d is provided in the bottom of the downstream region13 b of the air/liquid separation chamber 13 separated by the filter 12,and connected to the water treatment line 10.

On the other hand, an exhaust pipe 34 is connected to a portion of thecover 13 e covering the region 13 b. A blower F1 of suction type isprovided in the exhaust pipe 34. By driving the blower F1, gas resultingfrom the minute air bubbles removed from the treated water by the filter12 is forcibly expelled through the exhaust pipe 34.

An air introduction port not shown is provided in a portion of the cover13 e covering the region 13 a for introducing air into the air/liquidseparation chamber 13 in place of the gas expelled from the air/liquidseparation chamber 13.

FIG. 4 is a block diagram illustrating the electrical construction ofthe water treating device shown in FIG. 1. The water treating deviceincludes a control section 40 comprised of a microprocessor. Outputs ofthe residual chlorine sensor 26, the electrical conductivity sensor 24,the PH sensor 25 and the water level sensor W1 and outputs of the flowrate meters S1, S2 are applied to the control section 40. A memory and atimer are provided in the control section.

The control section 40 controls the operation of the water treatingdevice on the basis of detection signals applied thereto from therespective sensors and the flow rate meters in accordance with apredetermined operation program. More specifically, control signals areapplied to a driver 43. On the basis of the applied signals, the driver43 controls an electric current level to be applied to the electrode setE1 and an energization period. Further, the driver controls theopening/closing and regulating operations of the respective valves B1,B2, B3, B4, B7, B8, B9, B12, the driving of the circulation pump 22 andthe feed pump P1, and the driving of the blower F1.

Referring again to FIG. 2, the circulation pump 22 is first actuated,and a great amount of the to-be-treated water is constantly circulatedin the main circulation line 20 as shown by the double-line arrows forsterilization of the to-be-treated water in the water container 2 in thewater treating device 1. At the same time, the feed pump P1 is actuated,and all the valves B1, B2, B3, B4, B7, B8, B9, B12 are opened. Thus, apart of the to-be-treated water circulated in the main circulation line20 flows into the water treatment line 10. The flow rate of theto-be-treated water is regulated through the regulation valves B2, B3,and measured by the flow rate meter S1. The to-be-treated water havingthe flow rate regulated by the regulation valves B2, B12 is suppliedinto the residual chlorine sensor 26 for the measurement of the residualchlorine concentration. The flow rates at the regulation valves B2, B3are controlled according to the flow rate measured by the flow ratemeter S1.

The to-be-treated water having passed through the electromagnetic valveB4 is introduced into the upstream region 13 a of the air/liquidseparation chamber 13, and electrolyzed by the electrode set E1 in theregion 13 a. The energization of the electrode set E1 is controlled onthe basis of the residual chlorine concentration measured by theresidual chlorine sensor 26. The water sterilized through theelectrochemical reaction is fed into the downstream region 13 b throughthe filter 12. At this time, the minute air bubbles are removed by thefilter 12, whereby apparently clear and clean water is obtained.

The gas resulting from the minute air bubbles removed from the treatedwater at the passage through the filter 12 is expelled from the chamberthrough the exhaust pipe 34 by the driving of the blower F1.

The water sterilized and freed from the minute air bubbles flows out ofthe outlet port 13 d into the water treatment line 10 by the action ofthe feed pump P1, and passes through the flow rate meter S4, theregulation valve B7, the check valve B8 and the regulation valve B9thereby to be returned into the main circulation line 20 at the junctionJ2. Thus, the water is fed back into the water container 2.

Next, an explanation will be given to the construction of the residualchlorine sensor 26.

FIG. 5 is a diagram schematically illustrating the construction of theresidual chlorine sensor 26 employed in the water treating device ofFIG. 1. The residual chlorine sensor 26 has an overflow chamber 60 andan electrode device 61. The bypass line 11 diverged from the watertreatment line 10 is connected to the overflow chamber 60 via theregulation valve 12. A feed pipe 60 a is connected to the overflowchamber 60, so that the to-be-treated water supplied into the overflowchamber 60 is further supplied into the electrode device 61 through thefeed pipe 60 a. A drain pipe 60 b is connected to the overflow chamber60, so that the to-be-treated water not flowing into the supply pipe 60b in the overflow chamber 60 flows into the drain pipe 60 b. That is,the to-be-treated water overflowing the overflow chamber 60 flows out ofthe overflow chamber 60 through the drain pipe 60 b, and is introducedthrough the bypass line 11 into the air/liquid separation chamber 13provided below the overflow chamber.

The electrode device 61 has a housing 61 a and an electrode 61 bdisposed in the housing 61 a. The feed pipe 60 a connected to theoverflow chamber 60 is inserted in the housing 61 a, and the lowermostoutlet port 60 c is located in the vicinity of a distal end of theelectrode 61 b at the bottom of the housing 61 a. Further, an outletpipe 61 b is connected to a side wall of the housing 61 b. The outletpipe 61 b is connected to the drain pipe 60 b, and further connected tothe bypass line 11.

The to-be-treated water supplied from the overflow chamber 60 throughthe feed pipe 60 a is accumulated in the housing 61 a. The water comesinto contact with the distal end of the electrode 61 b, then falls intothe bypass line 11 through the outlet pipe 61 b by gravity, and flowsinto the air/liquid separation chamber 13. At this time, the residualchlorine concentration of the to-be-treated water is measured by theelectrode 61 b.

With the use of the electrode 61 b, the residual chlorine concentrationis measured by a polarography method. For the measurement by thepolarography method, a detection electrode (gold electrode) and acounter electrode (silver-silver chloride electrode) not shown aredisposed in opposed relation in the to-be-treated water, and a voltageis externally applied between the electrodes. This method is based on afact that an electric current flowing between the detection electrodeand the counter electrode according to the voltage is proportional tothe residual chlorine concentration. By this method, the residualchlorine concentration of the to-be-treated water is determined on thebasis of the value of the electric current flowing between theelectrodes.

Although the explanation has been given to the construction of theresidual chlorine sensor 26 based on the polarography method suitablefor long-term continuous measurement, the residual chlorine sensor isnot limited thereto. For example, a residual chlorine meter forcontinuous measurement by a galvanic electrode method or aspectrophotometric method may be employed

FIG. 6 is a diagram illustrating the construction of a water treatingdevice according to a second embodiment of the present invention. Thewater treating device according to the second embodiment is differentfrom the water treating device according to the first embodiment in thata batch process electrolyzing chamber 14 is provided in place of theair/liquid separation chamber 13.

An electrode set E2 consisting of a plurality of electrode plates isprovided in the batch process electrolyzing chamber 14. The batchprocess electrolyzing chamber 14 is filled with an electrolytic solutioncontaining chlorine ions such as afforded by salt and having a functionof promoting an electrochemical reaction and, in this state, theelectrolytic solution is electrolyzed for a certain period of time byenergization of the electrode set E2, whereby a sterilizing liquidhaving a sterilizing capability is produced. The sterilizing liquid thusproduced is stored in a reservoir tank 14 d, and supplied from thereservoir tank 14 d to a main circulation line 20 through a feed line 35as required.

The construction will more specifically be described. The feed line 35is diverged at a branch J1 from the main circulation line 20 forcirculating to-be-treated water from a water container 2. The feed linejoins the main circulation line 20 at a junction J2 downstream of a heatexchanger 23. A stop valve B1, a regulation valve B5, an electromagneticvalve B6, the batch process electrolyzing chamber 14, a feed pump P2, acheck valve B8 and a regulation valve B9 are provided in this order inthe direction of the flow of the to-be-treated water in the feed line35.

Further, a salt water tank 31 storing therein the electrolytic solution,e.g., saturated salt water, is connected to the feed line 35 at aposition between the electromagnetic valve B6 and the batch processelectrolyzing chamber 14 via a metering pump P3. A water feed line 29diverged from the feed line 35 at a position between the stop valve B1and the regulation valve B5 is connected to the salt water tank 31. Aregulation valve B10 and an electromagnetic valve B11 are provided inthe water feed line 29. A float switch 32 is provided in the salt watertank 31. The electromagnetic valve B11 is opened and closed on the basisof the switching of the float switch 32, whereby the to-be-treated wateris supplied into the salt water tank 31 via the water feed line 29 toconstantly store the salt water at a predetermined water level.

A bypass line 41 is diverged from the main circulation line 20 at aposition between a filter 21 and the heat exchanger 23. The bypass line41 joins the main circulation line 20 downstream of the junction J2. Aconstant flow rate valve B11, a residual chlorine sensor 26 and a flowswitch 27 are disposed in this order in the direction of the flow of theto-be-treated water in the bypass line 41. The constant flow rate valveB11 controls the flow rate of the to-be-treated water supplied into theresidual chlorine sensor 26 at a constant level. The flow switch 27senses whether the to-be-treated water flows in the bypass line 41.

FIG. 7 is a schematic sectional view for explaining the construction ofthe batch process electrolyzing chamber 14. FIG. 8 is a schematic topview for explaining the construction of the batch process electrolyzingchamber 14. The batch process electrolyzing chamber 14 includes abox-shaped case body 14 a and a cover 14 b which covers an open top ofthe case body 14 a. A square resin box is separately provided as anelectrolyzing chamber 14 c in the case body 14 a. A space exclusive ofthe electrolyzing chamber 14 c in the case body 14 a serves as areservoir tank 14 d for storing the sterilizing liquid produced in theelectrolyzing chamber 14 c.

The electrode set E2 consisting of the plurality of electrode plates areprovided in the electrolyzing chamber 14 c. An end of the feed line 35is inserted in the electrolyzing chamber 14 c through the cover 14 b, sothat the electrolytic solution obtained by mixing the saturated saltwater pumped out of the salt water tank 31 with the to-be-treated watersupplied from the feed line 35 is supplied into the electrolyzingchamber 14 c.

The concentration of the electrolytic solution to be supplied into theelectrolyzing chamber 14 c is determined on the basis of the value of anelectric current flowing through the electrode set E2. The concentrationof the electrolytic solution is adjusted at an optimum level bycontrolling the flow rate at the metering pump P3 for pumping out thesaturated salt water and the opening and closing of the electromagneticvalve B6 for supplying the to-be-treated water for dilution. Thus, theelectrolysis by the electrode set E2 is controlled to be performed mosteffectively.

In the case body 14 a serving as the reservoir tank 14 d, a suction port35 a provided at an end of a latter half of the feed line 35 is locatedat the bottom of the reservoir tank 14 d. The feed pump P2 is providedin the midst of the feed line 35.

A water level sensor W2 required for controlling the level of thesterilizing liquid in the reservoir tank 14 d within a predeterminedrange is attached to a central portion of the cover 14 b. The waterlevel sensor W2 has a plurality of electrode rods SW1 to SW5 extendingdownward from the cover 14 b. The water level sensor W has the sameconstruction as the water level sensor W1 provided in the air/liquidseparation chamber 13 described in the first embodiment. Therefore, likecomponents disposed in like positions are denoted by like referencecharacters, and no explanation will be given thereto.

The cover 14 b has an exhaust pipe 33 for forcibly expelling gasgenerated by the electrolysis in the electrolyzing chamber 14 c from thecase body 14 a. A blower F2 is inserted in the exhaust pipe 33, so thatthe gas is sucked out through the exhaust pipe 33 by driving the blowerF2.

In the electrolyzing chamber 14 c, the supplied electrolytic solution iselectrolyzed to produce the sterilizing liquid in which hypochlorousacid and hypochlorite ions are dissolved. The sterilizing liquid thusproduced is filled in the electrolyzing chamber 14 c, and overflows froman upper portion of the electrolyzing chamber 14 c thereby to beaccumulated in the reservoir tank 14 d.

Upon the detection of the level of the sterilizing liquid in thereservoir tank 14 d by the water level sensor W2, the driving of themetering pump P3 and the opening and closing of the electromagneticvalve B6 are controlled on the basis of a detection output. Thus, theamount of the electrolytic solution to be introduced into theelectrolyzing chamber 14 c is controlled. The amount of the sterilizingliquid overflowing the electrolyzing chamber 14 c is indirectlycontrolled, so that the level of the sterilizing liquid in the reservoirtank 14 d is controlled at the predetermined level.

The water treating device having the batch process electrolyzing chamber14 operates in the following manner.

Referring mainly to FIG. 6, the water is pumped out of the watercontainer 2 by a circulation pump 22. After organic substances areremoved from the water by the filter 21, the water is diverged at thebranch J1, so that a part of the water is fed back into the watercontainer 2 through the heat exchanger 23 and a part of the water flowsinto the feed line 35.

A part of the to-be-treated water circulated in the main circulationline 20 flows into the bypass line 41, and the flow rate thereof isregulated at a substantially constant level by the constant flow ratevalve B11. Then, the residual chlorine concentration is measured by theresidual chlorine sensor 26. Thereafter, the to-be-treated water passesthrough the flow switch 27 and is returned into the main circulationline 20.

A part of the water flowing into the feed line 35 is fed into theelectrolyzing chamber 14 c of the batch process electrolyzing chamber 14after the flow rate thereof is regulated by the regulation valve B5. Apart of the to-be-treated water is fed into the salt water tank 31through the regulation valve B10 and the electromagnetic valve B11.Since NaCl is preliminarily provided in the salt water tank 31, NaCl isdissolved in the to-be-treated water flowing into the salt water tank 31to provide the saturated salt water. The saturated salt water in thesalt water tank 31 is pumped out into the electrolyzing chamber 14 c bythe operation of the metering pump P3. At this time, the saturated saltwater is mixed with the to-be-treated water flowing through the feedline 35 to provide the electrolytic solution.

The electrolytic solution flowing into the electrolyzing chamber 14 c iselectrolyzed by the energization of the electrode set E2 to provide ahigh concentration sterilizing liquid. The sterilizing liquid overflowsthe electrolyzing chamber 14 c, and is stored in the reservoir tank 14d. The amount of the sterilizing liquid in the reservoir tank 14 d isdetected by the water level sensor W2. When the level of the sterilizingliquid reaches the predetermined level, the supply of the electrolyticsolution from the circulation line 35 is stopped on standby.

The sterilizing liquid stored in the reservoir tank 14 d is supplied asrequired on the basis of the result of the measurement of the residualchlorine concentration performed by the residual chlorine sensor 26.That is, the feed pump P2 is driven as required, so that the sterilizingliquid flows through the feed line 35 and then into the main circulationline 20 at the junction J2 and is returned into the water container 2.

Referring to FIG. 9, an explanation will be given to the construction ofthe residual chlorine sensor 26 employed in the water treating deviceaccording to this embodiment. In this embodiment, the residual chlorinesensor 26 is of in-line type employing the polarography method. Themeasurement employing the polarography method is performed in the samemanner as in the first embodiment and, therefore, no explanation will begiven thereto.

The residual chlorine sensor 26 includes a housing 37, an electrode 38disposed in the housing 37, and a cover 39 which covers an open top ofthe housing 37.

A tail pipe 50 of the bypass line 41 on an inlet side is inserted in thehousing 37 through the cover 39, and an outlet port 50 a thereofgenerally faces the bottom of the housing 37. The cover 29 is furtherconnected to the bypass line 41 on an outlet side, and the flow switch27 is provided in the bypass line 41.

The flow switch 27 senses whether the to-be-treated water flows throughthe bypass line 41. Where it is judged that the to-be-treated water doesnot flow through the bypass line 41 with the flow switch 27 being off,for example, the to-be-treated water is not supplied into the residualchlorine sensor 26, so that accurate measurement of the residualchlorine concentration is difficult. In such a case, a control sectionnot shown causes information means to give information to a systemadministrator, and interrupts the operation of the water treatingdevice. Since the flow switch 27 is provided immediately downstream ofthe residual chlorine sensor 26, a failure in the supply of theto-be-treated water in the residual chlorine sensor 26 can assuredly bedetected which may occur due to water leakage or clogging of the bypassline 41.

A multiplicity of beads 52 are contained in the housing 37 in contactwith the electrode 38 provided in the bottom of the housing 37. Theto-be-treated water flowing into the bottom of the housing 37 from theoutlet port 50 a agitates the beads 52. The agitated beads 52 arebrought into contact with the electrode 38, whereby the electrode 38 iscleaned for constantly ensuring the accurate measurement of the residualchlorine concentration.

The control section not shown compares the residual chlorineconcentration of the to-be-treated water measured by the electrode 38 ofthe residual chlorine sensor 26 with a reference concentration stored ina memory. Where the residual chlorine concentration of the to-be-treatedwater is below the reference concentration, a control signal is appliedto the driver. Then, the feed pump P2 is driven for a predeterminedperiod to supply the sterilizing liquid into the water container 2.Thus, the residual chlorine concentration of the water container 2 isadjusted, so that the water in the water container 2 is kept clean.

In this embodiment, the circulation pump 22 provided in the maincirculation line 20 is utilized for supplying the to-be-treated water tothe bypass line 41. However, a pump dedicated for supplying theto-be-treated water into the bypass line 41 may be provided.

In this embodiment, the bypass line 41 is diverged from the maincirculation line 20 downstream of the filter 21, and joins the maincirculation line 20 downstream of the heat exchanger 23. Alternatively,the bypass line may be diverged from the main circulation linedownstream of the filter 21 and join the main circulation line upstreamof the circulation pump 22.

FIG. 10 is a diagram schematically illustrating the construction of awater treating device incorporated in a large-scale water container 2 inaccordance with a third embodiment of the present invention.

The construction of the water treating device shown in FIG. 10 ischaracterized in that a feed line 35 having a batch processelectrolyzing chamber 14 as described in the second embodiment isconnected parallel to a water treatment line 10 having an air/liquidseparation chamber 13 as described in the first embodiment.

The water treating device shown in FIG. 10 is constructed such that abypass line 41 is diverged from a main circulation line 20 and aresidual chlorine sensor 20 is disposed in the bypass line as in thesecond embodiment. Therefore, the bypass line 11 and the residualchlorine sensor 26 provided in the water treatment line 10 in the firstembodiment are not provided.

Alternatively, the construction of the first embodiment in which thebypass line 11 is provided in the water treatment line 10 and theresidual chlorine sensor 26 is provided in the bypass line may beemployed without the provision of the bypass line 41 and the residualchlorine sensor 26 in the main circulation line 20.

Since the other construction is such that the arrangement of the firstembodiment is connected parallel to the arrangement of the secondembodiment, like components are denoted by like reference numerals, andno explanation will be given thereto.

FIG. 11 is a block diagram illustrating the electrical construction ofthe water treating device shown in FIG. 10 in accordance with the thirdembodiment of the present invention. The water treating device includesa control section 40 and a driver 43. Detection signals of the residualchlorine sensor 26, an electrical conductivity sensor 24, flow ratemeters S1, S2, a flow switch 27, a PH sensor 25 and water level sensorsW1, W2 are applied to the control section 40. The control section 40controls the operation of the water treating device on the basis of thedetection signals from the respective sensors and the like in accordancewith an operation program. More specifically, control signals areapplied to the driver 43, which in turn controls the driving ofrespective valves B1 to B12, electrode sets E1, E2, feed pumps P1, P2, ametering pump P3, a circulation pump 22 and blowers F1, F2.

FIG. 12 is a flow chart for illustrating the flow of a control processto be performed by the control section 40 shown in FIG. 11,particularly, a water level detecting process to be performed byemploying the water level sensor W1 in the air/liquid separation chamber13.

When the power supply to the water treating device is turned on and therespective components of the water treatment line 10 are actuated tointroduce the to-be-treated water into an upstream region 13 a of theair/liquid separation chamber 13, the control section 40 checks whetherelectrical connection to an electrode rod SW4 is established (Step S1).

In Step S1, a check for abnormal water shortage is made. At the initialstage of the operation, the water level does not reach the electrode rodSW4, so that the water supply to the air/liquid separation chamber 13 iscontinued with the electrode valve B4 being open and with the feed pumpP1 being off (Steps S17, S18). Information on water shortage isdisplayed on a display section not shown, and energization of theelectrode set E1 is kept off (Steps S19, S20). Then, the process goes toStep S12.

In Step S12, a check for an abnormal water full state is made. In anormal state, electrical connection to an electrode rod SW1 fordetection of an abnormal water full state is not established, so thatthe process returns to Step S1 without any display. Thereafter, thewater is further supplied into the air/liquid separation chamber 13 and,if a water level is reached at which the electrical connection to theelectrode rod SW4 is established (YES in Step S1), it is checked whethera water level is reached at which electrical connection to an electroderod SW3 is established (Step S2).

In Step S2, it is checked whether the water level reaches a lower limitwater level. If it does not reach the lower limit water level with theelectrical connection to the electrode rod SW3 being not established (NOin Step S3), the timer is reset, and the electromagnetic valve B4 iskept open. Then, the process goes to Step S12 to make the check for theabnormal water full state, and the process returns to Step S1. Thus, thewater supply is continued, while the check for the abnormal water fullstate and the check for the abnormal water shortage are made.

When it reaches the lower limit water level with the electricalconnection to the electrode rod SW3 being established in Step S2, thetimer is started, and the feed pump P1 is actuated. Then, the display ofthe water shortage information is stopped, and a DC voltage is appliedto the electrode set E1 to start electrolysis of the to-be-treated water(Steps S3, S4, S5, S6). In Step S4, the feed rate at the feed pump P1 isset lower than the flow rate of the water to be supplied into theair/liquid separation chamber 13.

In Step S7, it is checked whether the water level reaches an upper limitwater level. If it does not reach the upper limit water level withelectrical connection to an electrode rod SW2 being not established (NOin Step S7), the process goes to Step S12 to make the check for theabnormal water full state. While the check for the abnormal watershortage is made in Step S1, Steps S1 to S6, S12 and S23 are repeatedlyperformed.

After it is confirmed that the water level reaches the lower limit waterlevel with the electrical connection to the electrode rod SW3 beingestablished in Step S2, the water level rises to the upper limit waterlevel and, if the electrical connection to the electrode rod SW2 isestablished (YES in Step S7), the electromagnetic valve B4 is closed tostop the water supply, and the timer is stopped (Steps S8, S9). Then,the process goes to Step S10.

In Step S10, it is judged whether the count of the timer is smaller thana reference period. If the count of the timer is smaller than thereference period, it is judged that an air/liquid separation filter 12is clogged, and information is given to a user by display means, abuzzer or the like not shown (Step S11).

On the other hand, if it is judged in Step S11 that no clogging occursin the filter 12 with the count of the timer being greater than thereference period, the process goes to Step S12 to make the check for theabnormal water full state. Then, the process returns to Step S1. Whilethe check for the abnormal water shortage is made, it is waited for thewater level to return to the lower limit water level (Steps S1 to S12and S23).

Since the water supply is stopped by closing the electromagnetic valveB4 in Step S8, the water level is gradually lowered. When the waterlevel is lowered to the lower limit water level and the electricalconnection to the electrode rod SW3 is interrupted (NO in Step S2), thetimer is started, and the electromagnetic valve B4 is opened again(steps S21, S22), whereby the water level in the air/liquid separationchamber 13 is constantly control at a level between the upper limitwater level and the lower limit water level.

If the water level in the air/liquid separation chamber 13 exceeds theupper limit water level due to some abnormality of the system, theelectrical connection to the electrode rod SW1 is established (YES inStep S12). Then, information on the abnormal water full state is givenby the display section, the buzzer or the like not shown and,immediately thereafter, the electromagnetic valve B4 and the feed pumpP1 are stopped and the energization of the electrode set E1 is stopped(Steps S13, S14, S15, S16). The check for the abnormal water full stateis constantly made during the water level detection controlling process.

If the water level is lowered below the lower limit water level due tosome abnormality of the system, the electrical connection to theelectrode rod SW4 is interrupted (NO in Step S1), and the process goesto Step S17. If the electromagnetic valve B4 is not open, theelectromagnetic valve B4 is opened for the water supply, and the feedpump P1 is stopped (Steps S17, S18). Then, information on the abnormalwater shortage is given to the user by the display section or the buzzernot shown, and the energization of the electrode set E1 is stopped(Steps S19, S20). Like the check for the abnormal water full state, thecheck for the abnormal water shortage is constantly made during thewater level detection controlling process.

FIG. 13 is a flow chart for illustrating the flow of a control processto be performed by the control section 40, particularly, a water leveldetection process to be performed by employing the water level sensor W2in the batch process electrolyzing chamber 14.

The sterilizing liquid produced in the batch process electrolyzingchamber 14 is supplied in a predetermined amount into the watercontainer 2 through the water treatment line 10 by actuation of the feedpump P2 only when the residual chlorine concentration of theto-be-treated water in the water container 2 is reduced below apredetermined level. Where the residual chlorine concentration satisfiesthe predetermined level, the feed pump P2 is kept off on standby.

When the power supply to the water treating device is turned on and therespective components of the feed line 35 are actuated to start thesupply of the electrolytic solution into an electrolyzing chamber 14 cof the batch process electrolyzing chamber 14, the control section 40first checks whether the electrical connection to an electrode rod SW4is established (Step S31).

In Step S31, a check for abnormal water shortage is made. In general,the water level does not reach the electrode rod SW4 at the initialstage of the operation. Therefore, the process goes to Step S45 forwater supply to the electrolyzing chamber by actuation of theelectromagnetic valve B6 for adjusting the amount of the to-be-treatedwater for dilution and actuation of the metering pump P3 for sucking outthe saturated salt water. Then, the electrode set E2 is energized tostart the electrolysis (Step S46). With the feed pump P2 kept off,information on the abnormal water shortage is displayed on the displaysection not shown (Steps S47, S48), and the process goes to Step S40.

In Step S40, a check for abnormal water full state is made. Sinceelectrical connection to an electrode rod SW1 for the detection of theabnormal water full state is not established in a normal state,information on the abnormal water full state is not displayed (StepsS40, S52), and the process goes to Step S31.

With the water supply continued, the electrolysis is performed for awhile. Then, the level of the sterilizing liquid in the electrolyzingchamber 14 c rises, and the sterilizing liquid overflows theelectrolyzing chamber 14 c thereby to be accumulated in a reservoir tank14 d. When the sterilizing liquid in the reservoir tank 14 d reaches theelectrode rod SW4, electrical connection to the electrode rod SW4 isestablished (YES in Step S31). Upon the establishment of the electricalconnection to the electrode rod SW4, the actuation of the feed pump P2is permitted, and the display of the information on the abnormal watershortage is stopped (Steps S32, S33). Then, the process goes to StepS34.

In Step S34, it is checked whether the water level reaches the lowerlimit water level with electrical connection to an electrode rod SW3established. If it does not reach the lower limit water level with theelectrical connection to the electrode rod SW3 not established (NO inStep S34), the process goes to Step S49, and the supply of theelectrolytic solution and the energization of the electrode set E2 arecontinued (Steps S49, S50). Then, the process goes to Step S38.

On the other hand, if it is confirmed that the water level reaches thelower limit water level with the electrical connection to the electroderod SW3 established (YES in Step S34), the process goes to Step S35.Then, it is checked whether the water level reaches the upper limitwater level with electrical connection to an electrode rod SW2established. If it does not reach the upper limit water level with theelectrical connection to the electrode rod SW2 not established (NO inStep S35), the process goes to Step S38.

In Step S38, it is judged whether a driving signal for the feed pump P2is present. If the residual chlorine concentration of the to-be-treatedwater in the water container 2 satisfies the predetermined level, thedriving signal for the feed pump P2 is not outputted, so that the feedpump P2 is kept off (Step S51). On the other hand, if the residualchlorine concentration of the to-be-treated water is lower than thepredetermined level, the control section outputs the driving signal forthe feed pump P2, and the feed pump P2 is driven for a predeterminedperiod, whereby the sterilizing liquid is supplied into the watercontainer 2 through the feed line 35 (Step S38, S39). Then, the processgoes to Step S40.

After the check for the abnormal water full state is made in Step S40,the process returns to Step S31. The supply of the electrolytic solutioninto the electrolyzing chamber 14 c is continued, and the sterilizingliquid overflowing the electrolyzing chamber 14 is accumulated in thereservoir tank 14 d, while the check for the abnormal water shortage andthe check for the abnormal water full state are repeated until the waterlevel reaches the upper limit water level with electrical connection toan electrode rod SW2 established.

Thereafter, the water level in the reservoir tank 14 d rises with thewater supply continued and, when it is confirmed that the water levelreaches the upper limit water level with the electrical connection tothe electrode rod SW2 established (YES in Step S35), the driving of theelectromagnetic valve B6 and the metering pump P3 is stopped to stop thesupply of the electrolytic solution into the electrolyzing chamber 14 c,and the energization of the electrode set E2 is stopped to stop theelectrolysis (Steps S36, S37). Then, the process goes to Step S40, andthe check for the abnormal water full state and the check for theabnormal water shortage are made in Steps S40 and S31, respectively, onstandby.

Thereafter, the driving signal for the feed pump P2 is outputted tosupply the sterilizing liquid into the water container 2 from thereservoir tank 14 d as required. Whenever the feed pump P2 is actuated,the level of the sterilizing liquid in the reservoir tank 14 d islowered, and the electrical connection to the electrode rod SW2 isinterrupted (No in Step S35). When the electrical connection to theelectrode rod SW3 is interrupted, the electromagnetic valve B6 and themetering pump P3 are actuated again, and the electrode set E2 isenergized to restart the electrolysis (Steps S34, S49, S50). Thereafter,the aforesaid control operation is repeatedly performed.

Where the water level in the reservoir tank 14 d exceeds the upper limitwater level due to some abnormality of the system, this is detected onthe basis of whether or not the electrical connection to the electroderod SW1 is established in Step S40. When the abnormal water full stateis detected, a process from Step S41 to Step S44 is performed. A controloperation for this process is substantially the same as the aforesaidcontrol operation, and no explanation will be given thereto.

In this embodiment, the batch process electrolyzing chamber 14 doublesas the reservoir tank 14 d, but may be provided separately from thereservoir tank 14 d. In this case, the aforesaid effects can be ensuredby providing water level sensors respectively in the electrolyzingchamber 14 c and the reservoir tank 14 d.

It should be understood that the present invention be not limited to theembodiments described above, but various modifications may be madewithin the scope of the present invention defined by the followingclaims.

This application claims priority benefits under the Convention on thebasis of Japanese Patent Applications No. 2001-131770 and No.2001-151537 filed with the Japanese Patent Office on Apr. 27, 2001, thedisclosure thereof being incorporated herein by reference.

1. A water treating device comprising: a water container for containingwater to be treated; an electrolyzing chamber for sterilizing theto-be-treated water by way of electrochemical decomposition byenergization of an electrode set consisting of at least two electrodeplates; a water treatment line through which the to-be-treated water isintroduced into the electrolyzing chamber from the water container andfed back into the water container after the sterilization of the waterin the electrolyzing chamber; a residual chlorine sensor for measuring aresidual chlorine concentration of the to-be-treated water before thewater is introduced into the electrolyzing chamber; and control meansfor controlling an amount of the to-be-treated water to be subjected tothe electrochemical decomposition in the electrolyzing chamber on thebasis of the residual chlorine concentration measured by the residualchlorine sensor to keep a residual chlorine concentration of the waterto be fed back into the water container within a predetermined range;wherein a bypass line is provided which is branched from the watertreatment line at a position upstream of the electrolyzing chamber forsampling the to-be-treated water, introducing the sampled to-be-treatedwater into the residual chlorine sensor for the measurement of theresidual chlorine concentration of the sampled to-be-treated water, anddischarging the sampled to-be-treated water into the electrolyzingchamber after the measurement.
 2. A water treating device as set forthin claim 1, wherein the residual chlorine sensor is located at aposition upper than the electrolyzing chamber in the bypass line.
 3. Awater treating device comprising: a water container for containing waterto be treated; an electrolyzing chamber for causing electrochemicaldecomposition by energization of an electrode set consisting of at leasttwo electrode plates; a feed line for filling the electrolyzing chamberwith an electrolytic solution containing chlorine ions and having afunction of promoting the electrochemical decomposition and, in thisstate, producing a sterilizing liquid having a sterilizing capability byway of electrolysis of the electrolytic solution by the energization ofthe electrode set, and supplying the produced sterilizing liquid intothe water container; a residual chlorine sensor for measuring a residualchlorine concentration of the to-be-treated water; and introductionamount controlling means for controlling an amount of the sterilizingliquid to be introduced into the water container on the basis of theresidual chlorine concentration of the to-be-treated water measured bythe residual chlorine sensor; wherein a bypass line is provided which isconnected to the water container for introducing the to-be-treated waterinto the residual chlorine sensor from the water container for themeasurement of the residual chlorine concentration of the to-be-treatedwater, and feeding the introduced to-be-treated water back into thewater container after the measurement.
 4. A water treating device as setforth in claim 1, wherein a filter device for filtering theto-be-treated water taken out of the water container and a constant flowrate valve for controlling a flow rate of the to-be-treated waterfiltered by the filter device at a substantially constant level areprovided upstream of the residual chlorine sensor.
 5. A water treatingdevice as set forth in claim 4, wherein the residual chlorine sensor isa residual chlorine sensor of in-line type.
 6. A water treating devicecomprising: a water container for containing water to be treated; anelectrolyzing chamber for causing electrochemical decomposition byenergization of an electrode set consisting of at least two electrodeplates; a feed line for filling the electrolyzing chamber with anelectrolytic solution containing chlorine ions and having a function ofpromoting an electrochemical reaction and, in this state, producing asterilizing liquid having a sterilizing capability by way of theelectrochemical decomposition of the electrolytic solution by theenergization of the electrode set, and supplying the producedsterilizing liquid into the water container; water level detecting meansfor detecting a water level in the electrolyzing chamber; and waterlevel controlling means for controlling an amount of the sterilizingliquid to be introduced into the electrolyzing chamber on the basis ofwater level data from the water level detecting means to keep the waterlevel in the electrolyzing chamber at a predetermined level; wherein thewater level detecting means has at least two electrodes disposed inspaced opposed relation and is adapted to detect the water level on thebasis of whether an electric current flows between the electrodes.
 7. Awater treating device as set forth in claim 6, wherein the electrolyzingchamber comprises a tank for storing therein the produced sterilizingliquid and feeding the stored sterilizing liquid back into the watercontainer as required, wherein the water level controlling meanscontrols an amount of the sterilizing liquid to be produced in theelectrolyzing chamber on the basis of the data from the water leveldetecting means to keep a level of the sterilizing liquid stored in thetank at a predetermined level.
 8. A water treating device, comprising: awater container for containing water to be treated; an electrolyzingchamber for causing electrochemical decomposition by energization of anelectrode set comprising at least two electrode plates; a watertreatment line through which the to-be-treated water is introduced intothe electrolyzing chamber from the water container and fed back into thewater container after sterilization of the water by the electrochemicaldecomposition in the electrolyzing chamber; water level detecting meansfor detecting a water level in the electrolyzing chamber; and waterlevel controlling means for controlling an amount of the to-be-treatedwater to be introduced into the electrolyzing chamber on the basis ofwater level data from the water level detecting means to keen the waterlevel in the electrolyzing chamber at a predetermined level; wherein thewater level detecting means has at least two electrodes disposed inspaced opposed relation and is adapted to detect the water level on thebasis of whether an electric current flows between the electrodes; andwherein the electrodes of the water level detecting means are composedof a metal of titanium or a titanium alloy.
 9. A water treating deviceas set forth in claim 3, wherein a filter device for filtering theto-be-treated water taken out of the water container and a constant flowrate valve for controlling a flow rate of the to-be-treated waterfiltered by the filter device at a substantially constant level areprovided upstream of the residual chlorine sensor.
 10. A water treatingdevice as set forth in claim 9, wherein the residual chlorine sensor isa residual chlorine sensor of in-line type.
 11. A water treating deviceas set forth in claim 6, wherein the water level detecting means isdisposed in a space other than an inter-electrode space in theelectrolyzing chamber.
 12. A water treating device as set forth in claim11, wherein a resin separator for separating the electrode plates of theelectrolyzing chamber from the electrodes of the water level detectingmeans is disposed between the electrode plates and the electrodes.
 13. Awater treating device as set forth in claim 7, wherein the electrodes ofthe water level detecting means are composed of a metal of titanium or atitanium alloy.